Multiscale Fluidics

■Microfluidic technology is increasingly being applied to perform advanced biochemical analyses such as PCR in the sea. On the other hand, one challenge in microfluidics technology is that there is a limit to the amount of fluid that can be handled. In other words, microfluidic technology is advantageous for handling microliter- and nanoliter-level of ultrasmall volumes, but milliliter- and even liter-level volumes are difficult to handle in microfluidic devices as is. For example, in the case of analysis of marine microorganisms, if 1 ml of seawater is collected, it contains a large number of cells, so the microfluidic technology alone could handle everything from automated gene extraction to analysis by PCR, as demonstrated by the in situ gene analysis system. On the other hand, environmental DNA analysis for fish requires handling samples at the several hundred ml to liters level.

■As a technical solution, it seems that it would be possible to apply microfluidic technology to fish eDNA analysis by simply combining the appropriate in situ filtration and concentration capability. Actually, there are several commercially available instruments that filter and concentrate plankton and other biological particles in the marine environment. However, filtering and concentrating samples from liters-level seawater to extract and purify DNA also requires technology to deal milliliters-level fluids. Only after the DNA extraction operation, the process for eDNA analysis become the domain of microfluidics technology at the microliters level. In other words, for analyses that require large sample volumes, such as fish eDNA, their automation requires integrated control technology for multi-scale fluids from liters to microliters.

■Therefore, instead of using different technologies for each scale and combining them, I advocate "multi-scale fluid technology" as a universal technology that can be widely used for fluid control at different scales. Instead of using different technologies for each different scale, the realization of technologies that can be applied to various scales makes it possible to efficiently connect the analysis flow from the liters to the microliters scale.In addition, the cost for development, maintenance, and the acquisition of operation skills related to the use of the single functioned multiple instruments can be reduced.

■The microfabrication technologies that have been used to fabricate microfluidic devices can realize ultrasmall structures down to the nanometer level, but it takes time to be skilled and requires large-scale facilities to build-up practically applicable devices. Therefore, we are currently applying 3D printing technology in the development of in situ instruments. The use of 3D printer technology, which is rapidly developing year by year, makes it possible to fabricate both large and small objects at once across scales. We are currently conducting the R&D to realize a fully automated in-situ analyzer for marine eDNA, especially using a material jetting 3D printer and DLP 3D printers with support from the Ministry of Education, Culture, Sports, Science and Technology (MEXT) and the Japan Science and Technology Agency (JST).

＜Related Publications/ PR＞

福場辰洋「現場型自動装置を用いた環境DNA解析への展開」海を拓く現場計測研究会（リモート, 2021.10.4）

福場 辰洋「環境DNAサンプル自動採取装置の開発の現状と自動遺伝子解析への展開」Ocean DNAテック　環境DNA技術はどこまで進むか？（東京, 2021,6,30）

T. Fukuba, T. Fujii “Lab-on-a-chip technology for in situ combined observations in oceanography”, Lab on a Chip, 21(1), pp. 55-74. (Critical Review), DOI: 10.1039/D0LC00871K, 2020

T. Fukuba, Y. Sano, Application of 3D-Printed Microfluidic Device and Miniature Photodetection Technology Towards Photometry Based Biochemical Analysis in Deep Sea, The 23rd International Conference on Miniaturized Systems for Chemistry and Life Sciences (µTAS2019) (Oct 27-31, Basel, Switzerland) pp. 1158-1159, 2019

T. Fukuba, Y. Sano, H. Yamamoto, T. Miwa, and T. Fujii, “Development and improvement of miniaturized in situ bio/biochemical analysis systems towards multi-modal ocean sensing” UT’19 (Kaoshiung, Taiwan, 2019. 4.16-19), 2019

福場辰洋,「マイクロ流体技術による海洋化学・生化学計測」, 日本機械学会誌, 121, pp. 28-31, 2018